Cyclospora — the infamous “diarrhea parasite” sparking concern nationwide and a lettuce recall in 27 states — has sickened thousands in recent months. The intestinal infection is spread through contaminated food or water, and outbreaks are often linked to fresh produce.
Cyclosporiasis usually ramps up in the summer. But this year, it’s surging to unusually high levels across the United States.
Over 11,500 confirmed or probable cases have been reported in 41 states since May 1, per the Centers for Disease Control and Prevention. At least 308 people have been hospitalized so far. In an average year, the U.S. usually sees around 3,000 cases.
Most of the cases reported in the U.S. are part of a massive cyclosporiasis outbreak spanning five states: Michigan, Ohio, Indiana, Kentucky and West Virginia.
So far, health officials have identified shredded iceberg lettuce imported from Mexico and sold at Taco Bell as a potential source in the multistate outbreak, but investigations are ongoing. Experts recently told NBC News it’s likely that other sources are also causing sizable outbreaks.
Emergency medicine physicians are often the first responders for sudden gastrointestinal illness. TODAY.com spoke to ER doctors on the front lines of the cyclospora outbreak in Michigan about the most common symptoms and what people should know about the parasitic infection.
Cyclospora ‘Diarrhea Parasite’ Outbreak 2026
“It’s not atypical to see small outbreaks or occasional cases, and June and July tend to be the highest time, but this one seems particularly significant,” Dr. Jaime Hope, an emergency medicine physician at Corewell Health Emergency Center in Livonia, Michigan, tells TODAY.com.
“Usually it’s not filling our department, but I’ve had shifts where, gosh, maybe half of the people are there for a stool-related concern,” Hope adds.
As of July 23, Michigan has reported 7,664 cyclosporiasis cases and 160 hospitalizations, per the the Michigan Department of Health and Human Services. The state usually reports about 50 cases every year.
“We’re seeing many more people than we ordinarily would, and I think most of the people that have this infection are staying home and not even coming into the ER,” Dr. Brad Uren, an associate professor of emergency medicine at the University of Michigan Medical School, tells TODAY.com.
Among those who do come to the ER and test positive for cyclospora, they’re seeing some themes with symptoms.
Cyclosporiasis Diarrhea “Isn’t Subtle”
The hallmark symptom of cyclosporiasis is watery, sometimes “explosive” diarrhea. “It’s very urgent, (and) there’s a very large volume,” Uren says.
The bowel movements are often so frequent that they can disrupt daily life. “This isn’t subtle,” Hope emphasizes.
“When patients are coming in with diarrhea, it isn’t just, ‘hey I went a few times today.’ They often have to get up a few times while they’re trying to talk to staff,” Hope adds.
It can get so severe that patients develop rectal irritation. It’s not run-of-the-mill, occasional loose stools.
“Mostly, it’s frequent, watery diarrhea that’s been going on for days to weeks, and some people can even experience weight loss,” Dr. Daniel LaLonde, chair of the emergency department at Henry Ford St. John Hospital in Detroit, tells TODAY.com.
Parasite Causes Severe Cramping and Bloating
Another hallmark cyclosporiasis symptom is intense abdominal cramping, the experts note.
“People often describe it as feeling lots of gurgling and painful cramping before they have an episode,” says Uren.
The bloating may cause patients to pass excess gas. Hope says she’s seen many cyclosporiasis patients with significant flatulence, which can be associated with “unexpected diarrheal movements.”
Other Cyclospora Symptoms Include Extreme Fatigue
“What we’re also seeing a lot of patients report is fatigue, they’re exhausted,” says Hope.
The frequent, watery diarrhea causes the body to lose fluids rapidly, which can lead to dehydration or an electrolyte imbalance, LaLonde explains.
When the parasite infects the small intestine, it causes inflammation to the lining, making harder to absorb nutrients — which can cause people to feel zapped of energy.
The fatigue may continue after the intestinal symptoms stop, per the CDC.
Vomiting and Fever Are Not Common With Cyclosporiasis
When it comes to the symptoms of cyclosporiasis, “there’s a lot of overlap with other gastrointestinal illnesses,” says Uren.
However, one major distinction between cyclospora versus other types of food poisoning is that the parasitic infection typically occurs without vomiting, LaLonde notes.
“Certainly patients can be nauseated and have decreased appetite but, this hasn’t been as much of a vomiting illness,” Hope adds.
Aches and chills are possible with cyclosporiasis. “I have not seen as much low-grade fever,” says LaLonde.
Cyclospora Takes a While to Cause Symptoms
People who become infected with cyclospora won’t develop symptoms right away. So if you feel sick immediately after eating a salad, that likely isn’t the culprit.
“Patients will think it was something they ate hours ago, but for cyclospora, the incubation period is longer,” says Hope.
The time between exposure to the parasite and when symptoms first appear is two to 14 days. On average, it takes a week for the diarrhea to start.
“It can be hard to pinpoint where exactly it came from,” says LaLonde. By the time a person tests positive, it could be several weeks after they were exposed — at which point, remembering what you ate is a challenge.
“There’s a lot of guesswork,” says Hope.
Only a small portion of cyclosporiasis cases reported each year get traced back to a specific food.
Diagnosis Requires a Positive Cyclospora Test
Diarrhea can be caused by many viral, bacterial or parasitic infections, and these are still making people sick right now, the experts emphasize.
The only way to confirm if you have cyclosporiasis is to get tested, which requires a stool sample analysis, says Hope.
Cyclospora is not included in routine GI panels or parasite tests, so providers have to order specialized laboratory testing.
“I think I’ve ordered more in the last month or so than I have in the previous many years combined,” Hope adds.
The turnaround time for cyclospora testing is usually two to four days, so you won’t find out if you have the parasite right away.
The Parasite Isn’t Contagious
“One of the biggest questions we get from people is: Is it contagious?” says LaLonde.
The answer is no. “It’s almost impossible,” he adds.
People get cyclosporiasis by ingesting food or water contaminated with feces from an infected person.
Once the parasite is shed in stool, it takes one to two weeks living outside the body for cyclospora to grow and become infectious — that makes person-to-person transmission extremely unlikely.
How to Treat Cyclosporiasis
The first-line treatment is a combination antibiotic: trimethoprim-sulfamethoxazole (TMP-SMX). The typical course is seven to 10 days.
Typically, these antibiotics are only prescribed for confirmed cases. However, providers may initiate treatment before testing results come back if a patient has very severe symptoms consistent with cyclosporiasis, Hope adds.
Although the antibiotics to treat cyclospora are well-tolerated, there are possible side effects, including stomach upset.
“Treatment isn’t mandatory, but it does help stop the diarrhea and decrease the symptoms,” says Hope.
Most People Recover on Their Own
“If you are healthy and don’t have a suppressed immune system, you can beat this on your own,” says Uren.
It may take up to a month, Uren adds, but the majority of people will recover with supportive care, including rest and hydration.
After recovering, Hope recommends eating foods rich in probiotics to help shore up the good bacteria in your gut.
Cyclosporiasis Usually Isn’t Life-Threatening
The parasitic infection is rarely fatal, the experts note.
The vast majority of cyclospora patients won’t need to be hospitalized. “In regular outbreaks, it’s less than 5% of (those infected),” says Hope.
If complications do occur, they’re usually from dehydration. “We may see someone who has hypomagnesemia or hypokalemia, which is low magnesium or low potassium,” says LaLonde.
Some people are at higher risk of complications: the elderly, very young children, and immunocompromised individuals.
“The handful of people that I have admitted to the hospital (so far) have an abnormal immune system … so people with organ transplants or people receiving chemotherapy,” says Uren.
When to See a Doctor
If you have mild cyclosporiasis symptoms, the experts recommend contacting your health care provider. “Your regular doctor can order an outpatient test,” says Hope.
“We encourage people to undergo testing if they’re not getting better over the course of a few days to weeks,” LaLonde adds.
If you’re experiencing persistent or severe diarrhea, vomiting or other GI symptoms, seek medical care promptly.
People who are medically vulnerable — the elderly, young children, or the immunocompromised — should have a “much lower threshold” to get checked out, says Hope.
If you have signs of dehydration, go to your nearest emergency room, says Uren. These include extreme thirst, dry mouth, dark urine and dizziness.
The experts don’t recommend completely avoiding fresh fruits and vegetables, which are part of a healthy diet, but they encourage people to wash produce thoroughly before eating and stay informed about recalls.
